ProjectSummary?CoreC The Cell Biology Core provides major resources to the program project investigators, including normal human cells,anextensivelibraryofcharacterizedmelanomacelllinesandpatient-derivedxenografts(PDX)(Objective 1). The melanoma cell line library encompasses >400 cell lines, at least 200 with known genetic status. To exclude cross-contamination, all experimental cell lines are fingerprinted. Our normal cell panel includes: melanocytes, keratinocytes, fibroblasts, endothelial cells, and skin-derived stem cells. The PDX panel encompasses now >500 specimens. They have been characterized for metastasis formation and ~250 have beenanalyzedformutationsin108cancer-relatedgenes.Approximate50havebeensubjectedtoWholeExome Sequencingand RNAseq. >350PDXhave beenanalyzed forexpressionof>300 proteins. Weexpect thatall PDXwillbeanalyzedduringthecourseofthegrantatagenomewidelevelforabnormalitiesattheDNA,RNA and protein levels. Other resources include a lentiviral vectors for growth factors, adhesion molecules, and oncogenesandmonoclonalantibodiestomelanoma-associatedbiomarkers. Three-dimensionalculturesofnormalhumanskin(skinequivalentsororganotypicculturesofskin)withadermis of fibroblasts embedded in collagen and an epidermis of melanocytes/melanoma cells and keratinocytes, are alsocontinuouslyavailabletotheprograminvestigators(Objective2).Thisthree-dimensionalmodelissuperior to standard cell culture techniques because it mimics the in vivo microenvironment for the melanocytes/melanoma cells. For screening studies the Core is providing a robotics-assisted spheroid culture modelthatallowsinvestigationsonmelanomacellsdisplayinginvivorelevantarchitecture,cell-to-cellcontacts and invasion, inthepresence ofa collagen support matrix. Spheresare enriched in cancer stem-like cellsand canbeusedinsteadofspheroids.TheCoreadditionallyprovidessubcutaneousmelanomagrowthmodelsfor standard experiments, including patient-derived xenografts that are exclusively maintained in vivo and using tissuesprovidedbythePathologyCoreB.Avarietyofmetastasismodelsareavailableasarehumanizedmice tostudytheinteractionsofimmunecellswithtumorcells.